| composition | In chemistry, the kinds and numbers of atoms constituting a molecule. Origin: L. Compono, to arrange (05 Mar 2000) |
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| base composition | <biochemistry> In reference to nucleic acid, the proportion of the total bases consisting of guanine plus cytosine or thymine plus adenine base pairs. Usually expressed as a guanine + cytosine (G+C) value, for example 60% G+C. (09 Oct 1997) |
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| modeling composition | A thermoplastic material usually composed of gum damar and prepared chalk, used especially for making dental impressions. Synonym: impression compound, modeling composition, modeling compound. (05 Mar 2000) |